1. Field of the Invention
This invention relates to a method for measuring cell counts and/or methane producing activity of Methanogens in a Methanogens containing sample and, more particularly, it concerns a method which is applicable to the measurement of cell counts and/or methane producing activity of Methanogens existing in a multitude of microorganism groups and foreign substances such as digested sludge, for example, in a methane fermentation tank of a sewage treatment system.
2. Description of the Prior Art
FIG. 1 is a conceptional view, for example, of a modification based on a device for measuring the concentration of microorganism shown in ("Methodology for Microbiological Experiment", 206p, 1975, edited by Tomomichi Yanagida, published from Kodansha). In the figure, are shown an object for examination containing microorganisms, a light source 2, a power source 3 for applying a voltage to the light source 2, a photoelectric multiplying tube 4 opposed to the light source 2 by way of the object for examination 1, a power source 5 for applying a voltage to the photoelectric multiplying tube 4 and a detecting section for measuring the photocurrent from the electric multiplying tube 4.
In the following, explanations will be given as to a conventional method of measurement. Light emitted from the light source 2 transmits through the object for examination 1 containing microorganisms and the transmitted light is received by the photoelectric multiplying tube 4 and its intensity is measured by the detecting section 6 as a photocurrent value from the photoelectric multiplying tube 4. Since there is established a definite relationship between the absorbance and the concentration of microorganisms existing in the object for examination 1 when a visible light is used as the light source, the concentration of microorganism can be evaluated by measuring the absorbance as a result of or in connection with which, the cell counts or microbial activity can be evaluated.
Also, as another method for measuring the microbial activity, there has been a method of optically measuring a quantity of a biological substance related to the energy metabolism which is called "ATP" (Adenosine triphosphate) or "NAD(P)H" [Nicotinamide adenine Dinucleotide (phosphate)] contained in microorganisms.
As mentioned above, since the conventional method for measuring the cell counts or the activity of microorganism is to measure the absorbance of an object for examination, such method is effective so far as the object for examination is composed of only one kind of microorganism and no foreign substances such as sludge, etc. are contained in the object for examination. However, in the case where the object for examination is composed of various kinds of microorganisms and, moreover, foreign substances are contained therein, for example, as an object for examination in a methane fermentation tank where light is absorbed and scattered by and fluorescence is emitted from the substances, it was impossible to selectively measure the cell counts or the activity of a particular kind of microorganism which is desired to be measured. Further, since ATP and NAD(P)H are biological substances existing in all kinds of microorganisms, the method is not suitable for measuring the cell counts or the methane producing activity of Methanogens alone, and it results in a difficulty for continuously distinguishing ATP and NAD(P)H dissolved in the outside of the cells of microorganisms and other dissolved substances from ATP and NAD(P)H within the cells of the microorganisms.
One example of the prior art is disclosed as U.S. Ser. No. 694,384 (Japanese laid-open No. Sho 59-205998).